Rotary shaft coupling



July27, 1948. c. w. I-QIAWTHORNE 2,446,133

ROTARY SHAFT COUPLING Filed June 26, 1944 BY g f I A TTOR/VE? Patented July 27, 1948 l i r2,44c,133

noTaRYsnAF'r COUPLING Charles WI -Hatvthorne, Conneautville, Pa., I 'assignor to Morgan Construction Company,

chusetts r 1 5.Claims.

his invention relates forthetransmission ofpower, and more particu larly 'to"couplings*of the type having afrangible element arranged to serveas a safety device by limiting-the torque-transmitting capacity of the 'coupling'. l1 It is one object' of the invention to provide a safety coupling so constructed that its torque transmittiugcapacity may be predetermined-with considerableaccuracy. i

It isfa further obj ect' of the invention to pro- 'vide a comparatively simple and inexpensive safety "coupling which will suffer only minor damagewhen its torque-transmitting capacity is exceeded. l A v 'It is' a further object of the invention to provi'dea safety coupling havin an inexpensive frangible element' adapted to break when a pre deter-mined maximum torque isapplied to'the coupling, the construction being such that no damage' will be done to the otherparts of the coupling. i i I -With these andother objects in View, as will be apparent to those skilled in the art, the invention resides in the combination ofparts set forth-ih the" specification and covered by the claims appended hereto. H Referring to the drawings illustrating one em: bodiment of the invention and in which like ref erence numerals indicate like parts,

Fig. 1 is a longitudinal section through a rotary shaft coupling, taken on the line |l of Fig. 2; Fig. 2 is a section on the line 22 of Fig. 1;

Fig. 3 is an elevation of the coupling;

Fig. 4 is aperspective view of the driving element of the coupling;

Fig. 51s a perspective view of the driven elementofthecoupling; and

;.E1g.'-.6 is :a section similar to Fig. 2, but showing the; effect of: excessive torque on .the coupling.

The embodiment illustrated comprises a driving element I having a hub H keyed to a rotatable driving shaft l2 and provided with a flange I4. In axial alignment with the element In there is provided a driven element l5 having a hub l6 keyed to a rotatable driven shaft l8 and provided 'with a flange I9. The two fi'anges l4 and H! are spaced apart axially. At the center of the driving element I!) there is formed a projection 20 of non-circular cross section which extends toward the driven element ID. This projection 20 is preferably shaped as a cylinder with portions on opposite sides removed to provide two parallel plane surfaces 2| equidistant from the axis and connected by two convex cylindrical arcuate surfaces torotary shaft couplings Worcester, Mass a corporation of Massa ApplicationJunejZG, 1944, Serial No. 542,105 (01.64-28) 22 coaxial with the hub H. The driven element is provided with two diametrically opposed spaced lugs '24 which extend fromthe flange" l9 toward the flange Mon opposite sides of the projection 20. The inner surfaces of theselugs are preferably concave to conform with the curvature lof the surfaces 22 of thGDl'OjGCt-iOll 20, and the width of the lugs 24 is substantially equal to that of the projection." At the center of the projection 20 there is; provided a small cy lindrical pilot boss 21- which enters abushing 28 mounted in a recess 29 in the center of the driven element l5. This bushing 28 may boot the selflubricating type; Means is provided to prevent relative rotation of the =drivingand driven elements except under conditions of 'excessivetorque. For this purpose twoparallel generally rectangular flat bars 3| are mountedon opposite sides of the projection 20 to" engage the flat surf-aces 2| thereof and overlap thelugs 24. The ends of these bars areconnected by meansof two bolts 32-whichextend througl outwardly-open slots 33in the lugs 24. These bolts alsoextendthrough outwardly-open slots 35 in the ends '0f-=the :bars 3|. 'Recesses or counterboresfi36 are provided: in the bars 31 to receive the heads and nuts of the bolts. The central portions 31 of the bolts are preferably weaken ed by turning them down to a predetermined diameter. The inner surfaces of the bars3i are beveled near the endsof the-barsas shown-at 39.

The-operation:ofthe invention will now be apparent from the above disclosure. 'I'he driving shaft i2 -an'dthe driving element l llwill berotated by a suitable source of power, and the torque will be transmitted to the driven element i'5 throughi the medium of the bars- 3| and the bolts 32. These bolts will-be stressed intension} with the load. equally dividedbetween them to provide aforce couple. From the known strength of the bolt material, thedesigner can readily pre determine the diameter-of the portions 31 of the bolts necessary to transmit a desired torque without breaking. When this torque is exceeded, one or the other of the bolts will break, allowing the bars 3| to separate and the driven element 15 to remain stationary while the driving element I0 continues to rotate. The pilot boss 21 will aid in keeping the two parts of the coupling aligned under these conditions. Because of the beveled surfaces 39 on the bars 3|, it is not necessary that both the bolts should break to release the coupling. As shown in Fig. 6, upon breakage of one bolt the bars can separate at one end while rocking on the lug 24 at their other ends without ally aligned rotatable members, a projection extending from one member towardthe qtheri'mem- 1. A rotary shaft coupling comprising twoaxiher, the projection being shaped to provide two parallel plane surfaces equidistant from ithe -axis and connected by two convex cylindrical surfaces coaxial with the members, iWO illlgs extending from the said other member on opposite sides of the projection and having concave inner surf-aces conforming with the curvature of the said cylindrical-surfaces. the widthpf the lugs being substantially equal to that .of the projection, two parallel fiat barsmountedonoppositesides of the projectionto engage the said plane surfaces and overlap the lugs, theinner surfaces of the bars being beveled near the endsof thekbars, and tensiontdevices connecting the ends of the bars so arranged that @upon breakage ofioneof said defromthe saidtother memberon opposite sidesbf the projection and having c n aVeinnersurfaces conforming with the curvature ,of the said icylindrical surfacesthe width of the lugs heing substantiallytequal to'thallof the projection-two parallel flat bars mounted on opposite sides of'the projection to engagethesaid plane surfaces and overlapthe lugs, the endportions of-the barsand the lugs having aligned outwardly-open slots therein, and bolts located ,in-the slots 1to connect the ends of the bars andso arranged that upon breakage of the bolts the :barsimay separate to permit relative rotation of the two members.

3. A rotary shaft coupling comprising -;two coaxially mounted rotatable members, a projection extending from one member'and shaped to ,provide two parallel plane surfaces equidistant from theaxis, two lugs extending-from thexOllhBI member on opposite sides of the projection, the width of thelugsbeing substantiallyequalto that .ofthe projection, two parallel bars mountedon opposite sides of-the projection to engage the said plane 4 surfaces and overlap the lugs, the inner surfaces of the bars being beveled near the ends of the bars, and tension devices connecting the ends of the bars so arranged that upon breakage of one of said devices the corresponding ends of the bars may separate while the beveled surfaces at the other xends rock en the ;;adjacent 1ug ,;thus permitting relative -rctatio'n 'rOf the two members.

4. A rotary shaft coupling comprising two co- :zaxially mounted rotatable members, a projection .,eggtending. fpom one member, the projection being shaped to provide two parallel plane surfaces iequidistant from 'thBJaXiS and connected by two 'iconvex cylindrical surfaces coaxial with the mem- =.bers,'two ,lugs extending from the other member on opposite sides of the projection and having -::GO .Q&Ve,lI}ner surfaces conforming with the curvature of the said cylindrical surfaces, the Width of thelu'gs being substantially equal to that of the projection, two parallel fiat bars mounted on opposite sides of the projection to v engagewthe said plane surfaces and overlap the lugs, ;the inner surfaces of the bars ;being beveled near ;the ends of the bars, and tension devices -connectingcthe ends of the bars so arrangedthatv-llponrbreakage of one of said devices the correspon-dingi-endsigf the bars may separate whilethabeveledsurfaces at the-othenends rock on the-adjacent;'ll1g,;thu.$ permitting relative rotation .of \the two; members.

5. A rotary shaft couplingcomprisingtwo ;coaxially mounted rotatablmmembers, a projection extending from one-member,-.,theiprojection being shaped to -,pr ovide two parallel plane surfaces equidistant from the axis and. connected by :tWD convex cylindrical surfaces coaxial with themembers, two lugs extending fromthe other member on opposite sides of the projection and having concave inner surface conform n 'zw t ffihe 1. m vature of the said cylindrical surfaces, the width of the lugs being substantially,equal to thatofthe projection, two parallel flat bars mounted on one posite sides of the projection to engage thesaid plane surfaces and overlap the ,lllgs theend portions of theba-rs and the lugs having aligned outwardlyeopen slots;therein, and bolts ,locatedinthe slotsto connect the ends of the barsand soarranged that upon breakage of the =boltsthe;bars may separate to permit relative rotation .ofgthe twomembers.

ClI-lLAlFtllvliiS -W. HAWTHORNE.

REFERENCES, "CITED,

Thewfollowing references are of record in the file of this patent:

UNITED STATES V PATENTS .Spiller Now-14,1944- 

